Double-cavity heterogeneous micro-electrolytic tank based on theta-shaped glass tube and preparation method of double-cavity heterogeneous micro-electrolytic tank
A dual-cavity heterogeneous microelectrolysis cell based on a θ-type glass tube was prepared by using a dual-wire encapsulation and selective dissolution method. This method solves the problem of difficult integration of three electrodes during the miniaturization of microelectrolysis cells, achieves physical isolation of the electrodes and interface stability, and is suitable for various electrochemical detection methods.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- JINGGANGSHAN UNIVERSITY
- Filing Date
- 2026-01-28
- Publication Date
- 2026-05-12
AI Technical Summary
While pursuing miniaturization, existing microelectrolysis cell technology struggles to simultaneously achieve simple structure, convenient preparation, low cost, stable performance, universal functionality, and controllable interface, especially in terms of three-electrode integration and spatial isolation.
A dual-cavity heterogeneous microelectrolysis cell was prepared using a dual-wire encapsulation-selective dissolution method with a theta-shaped glass tube. The encapsulation tip was formed by laser drawing, and the metal wire was selectively dissolved to form a microchannel. After hydrophobic treatment and polishing, the working electrode and the counter/reference electrode were integrated to form an independent electrolyte pathway.
It achieves physical isolation between the working electrode and the counter/reference electrode, improves the stability of the liquid-solid interface and the reproducibility of the test, has a compact structure and is easy to mass-produce, is suitable for a variety of electrochemical detection, and has high integration and high yield.
Smart Images
Figure CN122016959A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the fields of electrochemical sensing and micro-area electrochemistry, specifically relating to a dual-cavity heterogeneous microelectrolysis cell based on a θ-type glass tube and its preparation method. Background Technology
[0002] Microelectrolytic cells have important applications in fields such as bioelectrochemical sensing, localized electrochemical impedance spectroscopy, and micro-area corrosion research. Traditional electrolytic cells are large in size and require large amounts of electrolyte, making it difficult to meet the needs of high spatial resolution electrochemical measurements of micron / nanoscale regions or extremely small samples (such as single cells and microdroplets).
[0003] In pursuit of miniaturization, existing technologies have proposed several solutions, but all have limitations to varying degrees. For example, integrating a three-electrode system on a chip using complex microelectromechanical systems (MEMS) processes can achieve miniaturization, but it suffers from cumbersome processes, high costs, difficulty in precisely controlling the electrode / solution interface, and potential signal cross-interference between different electrodes. To simplify the process, researchers have turned to utilizing the θ-type glass capillary structure. One approach (such as CN116626128A) involves depositing platinum nanoparticles through a long-term (12-24 hours) liquid-phase interface reaction at the tip of a single-sided capillary channel to construct a microcell for generating hydroxyl radicals. This approach has a long fabrication cycle, highly specific functionality (limited to radical generation), and both chambers are channel structures, failing to optimize the formation of the most stable electrode-liquid interface. Another approach (such as CN112305038B) involves integrating the working electrode (e.g., platinum-based iridium oxide) and the reference electrode (e.g., Ag / AgCl) into the dual cavities of a theta-shaped glass tube through filling and encapsulation processes, creating a composite electrode for pH detection. This method involves numerous steps (welding, drawing, and gel filling), essentially resulting in a symmetrical structure of "dual solid electrodes," making it difficult to easily modify into a universal sensing platform with heterogeneous integration of the "working electrode" and "independent electrolyte / counter electrode channels."
[0004] In summary, current microelectrolysis cell technology faces a common dilemma: while pursuing miniaturization, it is difficult to simultaneously achieve "simple structure, convenient fabrication, and low cost" and "stable performance, universal functionality, and controllable interface." It is either limited by complex and expensive microfabrication processes, or sacrifices structural optimization or functional universality in the pursuit of simplified processes. Therefore, there is an urgent need in this field for a new microelectrolysis cell design and fabrication method that can directly construct a miniaturized device with spatially isolated electrolyte pathways between the working electrode and the integrated counter / reference electrode, stable interface, and applicability to various electrochemical detection methods through a simple and reliable process. Summary of the Invention
[0005] To address the problems of difficulty in integrating three electrodes, poor spatial isolation, and complex fabrication processes in existing microelectrolysis cells, this invention provides a simple fabrication method for a dual-cavity heterogeneous microelectrolysis cell and its fabrication method, which enables physical isolation between the working electrode and the counter / reference electrode. Specifically, it provides a dual-cavity heterogeneous microelectrolysis cell based on a θ-type glass tube and its fabrication method.
[0006] The objective of this invention is achieved through the following technical solution: This invention first protects a preparation method, the core of which lies in "dual-wire encapsulation-selective dissolution". Specifically, this invention provides a method for preparing a dual-cavity heterogeneous microelectrolysis cell based on a θ-type glass tube, which includes the following steps: S1: Dual-wire encapsulation: A first metal wire and a second metal wire are respectively inserted into the middle of the two independent chambers of the θ-shaped glass tube. The diameters of the first metal wire and the second metal wire are both in the micrometer range. The middle of the θ-shaped glass tube is heated, sealed, and drawn using a laser drawing instrument to form the thinnest structure in the middle of the θ-shaped glass tube. The tube is then broken at the thinnest point to obtain two independent θ-shaped glass tubes, each with a tip. The first metal wire and the second metal wire are respectively encapsulated in the closed end of the tip of each θ-shaped glass tube. The tip has a conical structure.
[0007] S1a: Hydrophobic treatment of the outer wall: The outer wall of the tip of one of the θ-shaped glass tubes obtained in step S1 is hydrophobically treated; S2: Selective dissolution: Selectively dissolve the metal wire, i.e. the second metal wire, in one of the chambers of the θ-shaped glass tube obtained in step S1a, thereby forming a microchannel in the chamber at the tip, while the first metal wire in the other chamber is retained as the working electrode; S3: End face polishing: The tip of the θ-shaped glass tube obtained in step S2 is ground and polished to make the outlet of the microchannel, the end face of the first metal wire chamber, and the end face of the intermediate glass partition wall on the same plane. S4: Electrode assembly: After injecting electrolyte into the chamber where the microchannel is located, insert the counter electrode and the reference electrode; insert the third metal wire into the chamber containing the first metal wire, so that it contacts and conducts with the previously sealed first metal wire; that is, the electrolyte, the counter electrode and the reference electrode, the working electrode, and the third metal wire are assembled with the θ-shaped glass tube obtained in step S3 to form the dual-chamber heterogeneous microelectrolysis cell.
[0008] The hydrophobication treatment is a silanization treatment.
[0009] The silanizing agent used in the silanization treatment is one or a mixture of several of octadecyltriethoxysilane, dodecyltriethoxysilane, hexamethyldisilazane, octadecyltrichlorosilane, and dimethyldichlorosilane.
[0010] The specific method for selectively dissolving the second metal wire, which is located in one of the chambers of the θ-shaped glass tube obtained in step S1a, in step S2 is as follows: The tip of the θ-shaped glass tube obtained in step S1a is immersed in an etching solution to selectively dissolve the second metal wire. At this time, the first and second metal wires are metals with different chemical activities. The etching solution is a solution that can specifically dissolve the second metal wire without corroding the glass and the first metal wire. Alternatively, etching solution can be injected into the chamber containing the second metal wire to dissolve it. In this case, the first and second metal wires are metals with the same or different chemical activities.
[0011] The first metal wire is one of platinum wire, gold wire, silver wire, copper wire, or nickel wire; the second metal wire is copper wire or aluminum wire; the etching solution is a mixture formed by mixing deionized water, hydrochloric acid, and hydrogen peroxide, and the molar ratio of HCl to H2O2 in the etching solution is 2~5:1; the etching solution is prepared by mixing 50 mL of deionized water with 20 mL of 37 wt% hydrochloric acid and 10 mL of 30 wt% hydrogen peroxide to obtain the etching solution; Alternatively, the etching solution may be a 50% nitric acid solution.
[0012] In step S4, the counter electrode and the reference electrode are made of the same silver wire or a silver wire that has undergone chlorination treatment, i.e., Ag / AgCl wire.
[0013] The third metal wire is either a nickel wire or a copper wire.
[0014] The present invention also provides a dual-cavity heterogeneous microelectrolysis cell prepared by the above preparation method, which includes a θ-shaped glass tube body; the θ-shaped glass tube body is divided into a first chamber and a second chamber by an intermediate glass partition wall; the bottom end of the θ-shaped glass tube body is conical and is a heterogeneous closed end; The bottom of the first chamber is encapsulated with a first metal wire, and the upper end of the first metal wire is connected to a third metal wire, which extends out of the first chamber for connection to an external circuit via a wire; the diameter of the first metal wire is in the micrometer or nanometer range. The bottom of the second chamber is provided with an open microchannel, and the pore size of the microchannel is 10 μm to 500 μm. The second chamber is filled with electrolyte and a counter electrode and a reference electrode are inserted. The lower end face of the first chamber, the outlet of the microchannel, and the end face of the intermediate glass partition are polished to make them lie on the same plane.
[0015] The counter electrode and reference electrode inserted into the microchannel of the second chamber are Ag wires or Ag / AgCl wires, which serve as both counter and reference electrodes. The diameter of the Ag wire or Ag / AgCl wire matches the pore size of the microchannel, i.e., it is 10 μm to 500 μm. The first metal wire is one of platinum, gold, silver, copper, or nickel wire. The diameter of the first metal wire is 0.01 μm to 500 μm. The third metal wire is one of nickel or copper wire.
[0016] The present invention also provides a method for electrochemical detection using the aforementioned dual-cavity heterogeneous microelectrolysis cell, comprising the following steps: (1) Inject electrolyte into the second chamber containing microchannels; (2) Insert the counter electrode and the reference electrode into the microchannel of the second chamber; (3) A test droplet is formed on the end face of the heterogeneous closed end, so that the droplet simultaneously covers the end face of the working electrode and the outlet of the microchannel to form an electrochemical circuit; (4) Connect to an electrochemical workstation for testing.
[0017] Compared with the prior art, the advantages of the present invention are as follows: (1) Spatial isolation to avoid interference: The working electrode and the counter / reference electrode are located in two physically isolated chambers. By hydrophobizing the outer wall of the tip, it is ensured that the electrolyte droplets can be stably confined to the hydrophilic polished end face during the test, which greatly improves the stability of the liquid-solid interface and the reproducibility of the test.
[0018] (2) Unique structure and high integration: The heterogeneous structure of “solid electrode cavity / hollow channel cavity” created by selective dissolution perfectly integrates the three-electrode system in a tiny θ-shaped tip. The structure is compact and can realize the analysis of extremely small samples.
[0019] (3) The method is ingenious and the yield is high: The preparation method utilizes mature laser pulling technology to form two symmetrical pre-encapsulated tips in one step, and then selectively etches them by chemical method. The process has good repeatability and is easy to achieve mass production.
[0020] (4) Interface stability: The coplanar micro-interface formed after polishing ensures that the liquid-liquid / liquid-solid interface formed with the external droplets is stable and uniform, which is conducive to obtaining high-quality electrochemical signals. Attached Figure Description
[0021] Figure 1 This is a flowchart of the preparation method of the present invention.
[0022] Figure 2This is a schematic diagram of the θ-shaped glass tube obtained after steps S1 and S2 in Embodiment 1 of the present invention, wherein, Figure 2 a is a capillary optical microscope image of the copper and gold wires encapsulated in step S1. Figure 2 b is an optical microscope image of the closed end of the θ-shaped glass tube containing copper and gold wires encapsulated in step S1. Figure 2 c is an optical microscope image of the θ-shaped glass tube after the copper wire has been dissolved in step S2. Figure 2 d is an optical microscope image of the closed end of the θ-shaped glass tube after the copper wire has been dissolved in step S2.
[0023] Figure 3 This is a schematic diagram of the structure of the dual-cavity heterogeneous microelectrolysis cell prepared by the present invention.
[0024] Figure 4 This is a cyclic voltammogram of the gold electrode in the microelectrolysis cell obtained in Example 1 in sulfuric acid solution.
[0025] Figure 5 These are test images of the gold electrode in the dual-cavity heterogeneous microelectrolysis cell obtained in Example 1 in trichlorohexamineruthenium solutions of different concentrations; wherein, Figure 5 a represents the steady-state voltammetry curves of the gold electrode in the dual-cavity heterogeneous microelectrolysis cell of Example 1 in trichlorohexamineruthenium solutions of different concentrations. Figure 5 b is Figure 5 The linear fitting curve of the limiting diffusion current and solution concentration in a.
[0026] Labeling Explanation: 1. θ-type glass tube; 2. Intermediate glass partition; 3. First metal wire; 4. Second metal wire; 5. Laser drawing area; 6. Silanization solution; 7. Heterogeneous closed end; 8. Rotary polishing disk; 9. Working electrode; 10. Third metal (e.g., nickel wire); 11. Microchannel; 12. Ag wire or Ag / AgCl wire (counter / reference electrode); 13. Electrolyte; 14. External droplet. Detailed Implementation
[0027] The present invention will now be described in detail with reference to the accompanying drawings and embodiments: Example 1: A method for preparing a dual-cavity heterogeneous microelectrolysis cell based on a θ-type glass tube (the preparation process of the dual-cavity heterogeneous microelectrolysis cell is as follows) Figure 1 (As shown), it includes the following steps: S1: Dual-wire encapsulation: Take a section of borosilicate θ-type glass tube. Insert a 25 μm diameter gold wire (first metal wire 3) and a 50 μm diameter copper wire (second metal wire 4) into the middle of its two chambers respectively. Using a P-2000 laser drawing instrument, set appropriate heating programs and drawing parameters, laser heat and draw the middle region (laser drawing region 5) of the θ-type glass tube 1 until it breaks, obtaining two symmetrical pre-encapsulated parts (i.e., θ-type glass tubes with tips) with a tip diameter of approximately 500 μm. Each pre-encapsulated part has a gold wire (first metal wire 3) and a copper wire (second metal wire 4) encapsulated inside its tip, as shown. Figure 2 As shown in a and b.
[0028] S1a: Hydrophobic treatment of the outer wall: The outer wall of the tip of one of the θ-shaped glass tubes obtained in step S1 is hydrophobically treated; the specific steps are: prepare a solution with a concentration of 5% ( V / V An anhydrous ethanol solution of octadecyltriethoxysilane (OTEOS) was prepared, and 2% (by volume) of deionized water was added. After stirring, the solution was allowed to stand at room temperature for 15-30 minutes to hydrolyze, yielding silanized solution 6. The tip of the θ-shaped glass tube obtained in step S1 was completely immersed in this solution, and the reaction was carried out at room temperature for 12 hours. After the reaction, the glass tube was removed and thoroughly cleaned with anhydrous ethanol to remove the physically adsorbed unreacted silane reagent. The cleaned glass tube was dried with nitrogen and then heat-treated in an oven at 110°C for 1 hour to allow the silane layer to be firmly bonded to the glass surface through silicon-oxygen bonds (Si-O-Si), forming a stable hydrophobic film.
[0029] S2: Selective Dissolution: Selectively dissolve the metal wire (i.e., the second metal wire) in one chamber of the θ-shaped glass tube obtained in step S1a, thereby forming a microchannel in the chamber at that tip, while the first metal wire 3 in the other chamber is retained (e.g., ...). Figure 2 c, d), as working electrodes 9: The specific method is as follows: The tip of the θ-shaped glass tube obtained in step S1a is immersed in the etching solution. The etching solution selectively dissolves the copper wire (second metal wire 4) without significantly corroding the gold wire (first metal wire 3) or the θ-shaped glass tube 1. The dissolution process is monitored under a microscope until the copper wire is completely dissolved, and the cavity that originally encapsulated the copper wire forms a hollow microchannel 11. The cavity that encapsulated the gold wire remains unchanged, and the gold wire within it becomes the working electrode 9.
[0030] The etching solution is prepared by mixing 50 mL of deionized water with 20 mL of 37 wt% hydrochloric acid and 10 mL of 30 wt% hydrogen peroxide. Alternatively, the etching solution can be a 50% nitric acid solution, but its etching rate is slower than that obtained by mixing hydrochloric acid, hydrogen peroxide, and deionized water. Therefore, the etching solution prepared by mixing hydrochloric acid, hydrogen peroxide, and deionized water is preferred.
[0031] S3: End face polishing: The tip of the θ-shaped glass tube obtained in step S2 is ground and polished to make the end face of the microchannel outlet, the end face of the first metal wire chamber, and the end face of the intermediate glass partition wall on the same plane. The specific method is as follows: The θ-shaped glass tube obtained in step S2 is fixed on the micromanipulator, so that its tip contacts the rotating polishing disk 8 coated with fine diamond polishing powder at a specific angle, and is ground and polished until the end face of the working electrode 9 and the outlet of the microchannel 11 are observed to be on a smooth and flat plane under a microscope.
[0032] S4: Electrode Assembly: After injecting electrolyte into the chamber containing the microchannel, insert the counter electrode and reference electrode; insert the third metal wire (nickel wire 10) into the chamber encapsulated with the first metal wire, making it conductive with the previously sealed first metal wire; that is, the electrolyte, counter electrode, reference electrode, working electrode, and third metal wire are assembled into the θ-shaped glass tube obtained in step S3 to form the dual-chamber heterogeneous microelectrolysis cell. Specifically: Electrolyte 13 is injected into the second chamber forming the microchannel 11 from the open end of the θ-shaped glass tube, or the glass tube is inserted into the electrolyte 13 to fill the second chamber using capillary action, and an Ag / AgCl wire 12 treated with electrochemical chlorination is inserted as the counter electrode and reference electrode. A third metal wire (nickel wire 10) is inserted into the chamber encapsulated with the first metal wire 3 to make it conductive with the previously sealed first metal wire 3; that is, the electrolyte, counter electrode, reference electrode, working electrode, and third metal wire are assembled with the θ-shaped glass tube obtained in step S3 to form the dual-chamber heterogeneous microelectrolysis cell.
[0033] The dual-cavity heterogeneous microelectrolysis cell obtained from Example 1 is as follows: Figure 2 As shown, the prepared dual-chamber heterogeneous microelectrolysis cell is fixed, and the working electrode 9 is led out using nickel wire 10, which, along with the Ag / AgCl wire 12, is simultaneously connected to the electrochemical workstation. Using a microsyringe, a droplet 14 of the external liquid to be tested is dropped or dipped onto the end face of the polished heterogeneous closed end 7 (the tip of the θ-type glass tube). This droplet must simultaneously cover the end face of the working electrode 9 and the outlet of the microchannel 11. At this point, the circuit is connected, and electrochemical tests such as cyclic voltammetry can be performed.
[0034] like Figure 3As shown, the dual-cavity heterogeneous microelectrolysis cell obtained in Example 1 includes a θ-shaped glass tube 1 body; the θ-shaped glass tube 1 body is divided by an intermediate glass partition 2 to form a first chamber and a second chamber; the bottom end of the θ-shaped glass tube 1 body is conical and is a heterogeneous closed end; The bottom of the first chamber is encapsulated with a first metal wire 3, and the upper end of the first metal wire 3 is connected to a third metal wire 10, which extends out of the first chamber for connection to an external circuit via a wire. The first metal wire 3 serves as a working electrode 9. The diameter of the first metal wire 3 is in the micrometer or nanometer range. The bottom end of the second chamber is provided with an open microchannel 11, and the pore size of the microchannel 11 is 10 μm to 500 μm. The second chamber is filled with electrolyte 13 and a counter electrode and a reference electrode are inserted. The lower end face of the first chamber, the outlet of the microchannel 11, and the end face of the intermediate glass partition 2 are polished to make them lie on the same plane.
[0035] The counter electrode and reference electrode inserted in the microchannel 11 of the second chamber are Ag / AgCl wires (12), which serve as both counter and reference electrodes. The diameter of the Ag / AgCl wire matches the aperture of the microchannel 11, which is 10 μm to 500 μm. The first metal wire 3 is a gold wire. The diameter of the first metal wire 3 is 0.01 μm to 500 μm. The third metal wire 10 is a nickel wire.
[0036] Example 2: Basic electrochemical performance test of gold electrode in sulfuric acid solution The basic electrochemical response characteristics and electrode surface cleanliness of the dual-cavity heterogeneous microelectrolysis cell prepared by the method described in Example 1 of this invention, with gold wire (first metal wire 3) as the working electrode, were verified.
[0037] step: (1) Using the preparation method of the above embodiment, a dual-cavity heterogeneous microelectrolysis cell with a working electrode of 25 μm gold wire was prepared.
[0038] (2) Inject 0.5 M sulfuric acid (H2SO4) solution as electrolyte into the second chamber forming microchannel 11 from the open end of the θ-type glass tube, and then insert Ag wire as counter / reference electrode.
[0039] (3) On the polished end face of the micro-electrolysis cell, the solution is pushed out of the second chamber or a drop of 0.5 M H2SO4 solution is dipped to form an external droplet 14.
[0040] (4) Connect the working electrode and the counter / reference electrode to the electrochemical workstation. Perform cyclic voltammetry (CV) scans at a scan rate of 500 mV / s in the potential range of -0.25 V to +1.3 V (vs. Ag).
[0041] Results and Analysis: The obtained cyclic voltammetry diagram is shown below. Figure 4 As shown in the figure, a clear gold oxide formation peak is visible at approximately 0.9 V, and a corresponding reduction peak is visible near approximately +0.6 V, which is consistent with the characteristic redox behavior of bulk gold electrodes in sulfuric acid. Furthermore, the entire curve shows a low background current and a smooth non-Radidatic region (such as near 0 V), indicating that the micro-gold electrode prepared in this invention has a clean surface, good electrochemical activity, and reliable sealing and insulation performance.
[0042] Example 3: Performance test of quantitative detection of trichlorohexammonium ruthenium in a dual-cavity heterogeneous microelectrolysis cell Objective: To demonstrate the sensitivity and linearity of the microelectrolysis cell obtained in this invention as a sensing platform for quantitative analysis of analytes.
[0043] step: (1) Use the dual-cavity heterogeneous microelectrolysis cell with 25 μm gold wire as working electrode obtained in Example 1 or another dual-cavity heterogeneous microelectrolysis cell with 25 μm gold electrode prepared according to the method described in Example 1.
[0044] (2) Prepare a series of trichlorohexaammineruthenium (Ru(NH3)6Cl3) solutions of different concentrations (e.g., 0.005 mM, 0.05 mM, 0.1 mM, 0.2 mM) (with 0.1 M KCl as the supporting electrolyte).
[0045] (3) The test is carried out according to the steps described in Example 2. During each test, the test solution is injected into the encapsulated electrode chamber of the dual-cavity heterogeneous microelectrolysis cell and an external droplet 14 is formed on the end face.
[0046] (4) Connect the working electrode and the counter / reference electrode to the electrochemical workstation. Perform cyclic voltammetry (CV) scans at a scan rate of 50 mV / s in the potential range of -0 V to -0.45 V (vs. Ag / AgCl).
[0047] Results and Analysis: 1. Steady-state voltammetry curves: Steady-state voltammetry curves obtained from solutions of different concentrations are shown below. Figure 5 As shown in (a), all curves exhibit a typical plateau-shaped steady-state current, which is characteristic of the microelectrode under fully diffused conditions, indicating that the dual-cavity heterogeneous microelectrolysis cell of the present invention has good mass transfer performance and fast response capability.
[0048] 2. Linear calibration curve: The limiting diffusion steady-state current value corresponding to each concentration is linearly fitted to the solution concentration, and the results are as follows: Figure 5 As shown in (b). Data shows that within the concentration range of 0.1 mM to 5.0 mM, the steady-state current exhibits a good linear relationship with the concentration, and the linear correlation coefficient (R0) is [value missing]. 2 The value is greater than 0.99. This strongly demonstrates that the dual-cavity heterogeneous microelectrolysis cell provided by this invention can be used for high-precision quantitative electrochemical analysis, and its sensitivity can be characterized by the slope of this straight line.
[0049] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.
Claims
1. A method for preparing a dual-cavity heterogeneous microelectrolysis cell based on a θ-type glass tube, characterized in that: It includes the following steps: S1: Dual-wire encapsulation: A first metal wire and a second metal wire are respectively inserted into the middle of the two independent chambers of the θ-shaped glass tube. The diameters of the first metal wire and the second metal wire are both in the micrometer range. A laser drawing instrument is used to heat, seal, and draw the middle of the θ-shaped glass tube to form the thinnest structure in the middle of the θ-shaped glass tube. The tube is then broken at the thinnest point, resulting in two independent θ-shaped glass tubes, each with a pointed tip. The first metal wire and the second metal wire are respectively encapsulated in the closed end of the pointed tip of each θ-shaped glass tube. The pointed tip has a conical structure. S1a: Hydrophobic treatment of the outer wall: The outer wall of the tip of the θ-shaped glass tube obtained in step S1 is hydrophobically treated; S2: Selective dissolution: Selectively dissolve the metal wire, i.e. the second metal wire, in one of the chambers of the θ-shaped glass tube obtained in step S1a, thereby forming a microchannel in the chamber at the tip, while the first metal wire in the other chamber is retained as the working electrode; S3: End face polishing: The tip of the θ-shaped glass tube obtained in step S2 is ground and polished to make the outlet of the microchannel, the end face of the first metal wire chamber, and the end face of the intermediate glass partition wall on the same plane. S4: Electrode assembly: After injecting electrolyte into the chamber where the microchannel is located, insert the counter electrode and the reference electrode; insert the third metal wire into the chamber containing the first metal wire, so that it contacts and conducts with the previously sealed first metal wire; that is, the electrolyte, the counter electrode and the reference electrode, the working electrode, and the third metal wire are assembled with the θ-shaped glass tube obtained in step S3 to form the dual-chamber heterogeneous microelectrolysis cell.
2. The preparation method according to claim 1, characterized in that: The hydrophobication treatment is a silanization treatment.
3. The preparation method according to claim 2, characterized in that: The silanizing agent used in the silanization treatment is one or a mixture of several of octadecyltriethoxysilane, dodecyltriethoxysilane, hexamethyldisilazane, octadecyltrichlorosilane, and dimethyldichlorosilane.
4. The preparation method according to claim 1, characterized in that: The specific method for selectively dissolving the metal wire, i.e., the second metal wire, in one of the chambers of the θ-shaped glass tube obtained in step S1a in step S2 is as follows: the tip of the θ-shaped glass tube obtained in step S1a is immersed in an etching solution to selectively dissolve the second metal wire; at this time, the first metal wire and the second metal wire are metals with different chemical activities; the etching solution is a solution that can specifically dissolve the second metal wire without corroding the glass and the first metal wire; or an etching solution is injected into the chamber containing the second metal wire to dissolve the second metal wire; at this time, the first metal wire and the second metal wire are metals with the same or different chemical activities.
5. The preparation method according to claim 4, characterized in that: The first metal wire is one of platinum wire, gold wire, silver wire, copper wire, or nickel wire; the second metal wire is copper wire or aluminum wire. The etching solution is a mixture of deionized water, hydrochloric acid, and hydrogen peroxide. The etching solution is prepared by mixing 50 mL of deionized water with 20 mL of 37 wt% hydrochloric acid and 10 mL of 30 wt% hydrogen peroxide. Alternatively, the etching solution may be a 50% nitric acid solution.
6. The preparation method according to claim 1, characterized in that: In step S4, the counter electrode and the reference electrode are made of the same silver wire or a silver wire that has undergone chlorination treatment, i.e., Ag / AgCl wire.
7. The preparation method according to claim 1, characterized in that: The third metal wire is either a nickel wire or a copper wire.
8. A dual-cavity heterogeneous microelectrolysis cell prepared by the preparation method according to any one of claims 1-7, characterized in that: It includes a θ-shaped glass tube (1) body; the θ-shaped glass tube (1) body is divided by an intermediate glass partition (2) to form a first chamber and a second chamber; the bottom end of the θ-shaped glass tube (1) body is conical and is a heterogeneous closed end; The bottom of the first chamber is encapsulated with a first metal wire (3), and the upper end of the first metal wire (3) is connected to a third metal wire (10), and the third metal wire (10) extends out of the first chamber for connection to an external circuit via a wire; the diameter of the first metal wire (3) is in the micrometer or nanometer range. The bottom end of the second chamber is provided with an open microchannel (11), and the pore size of the microchannel (11) is 10 μm to 500 μm. The second chamber is filled with electrolyte and a counter electrode and a reference electrode are inserted. The lower end face of the first chamber, the outlet of the microchannel (11), and the end face of the intermediate glass partition (2) are on the same plane.
9. The dual-cavity heterogeneous microelectrolysis cell according to claim 8, characterized in that: The counter electrode and reference electrode inserted in the microchannel (11) of the second chamber are Ag wires or Ag / AgCl wires (12), which serve as both counter and reference electrodes. The diameter of the Ag wires or Ag / AgCl wires matches the aperture of the microchannel (11), which is 10 μm to 500 μm. The first metal wire (3) is one of platinum wire, gold wire, silver wire, copper wire or nickel wire. The diameter of the first metal wire (3) is 0.01 μm to 500 μm. The third metal wire (10) is one of nickel wire or copper wire.